Stay-bolt.



G. S. THOMPSON. STAY BOLT.

s'r Es 'rn'r orrrcn GEORGE s. THOMPSON, or nocxnssm, DELAWARE, ASSIGNORTo THE FLEXIBLE BOLT L COMPANY, A CORPORATION or DELAWARE.

7 .fbidllwhom it may awm STAYLPBOLT.

Be it known thatLI, GEO GES. Tnorrrson,

a citizenofthe United/States, residing in 'I-Iockessin, county ofNewcastle, and State ltl) bf'Delaware, havejnvented certain new andllseful'. Improvements .1n "Stay-Bolts, of

.aithiohihgfsillowing i'scas'pecification.

MZY improvements relate toxstaybolts having metal shanks of relativelyhigh tensile strength provided with a head or heads of "1a softermetal.Whilen'ot restricted thereto, m staylbo'lt is designedmore' especially.for

' use between'thezfire boxes and the outer .shells of boilers,particularly locomotive boilers, in which, owing to the'inequalityendvariability of'expansion of the fire loo'x pIatsaSQcoinpared. withthe outer boiler shell,-thfe st ay bolts are subjected to severelateral-strain. I

One ob-"ect-of my invention s to prov de means for fastening a stay.bolt of this chap acterto the boiler sheets named withoutv thenecessity of riveting the ends, or where the riveting of 'one'en'disdesirable, to obviate the necessity of subjecting the shank to thethrust and 'impact oft-he riveting operation;

. Another object is to provide for the adjustment of the length of thebolt within itself, to compensate for slight variations of distancebetween the boiler sheets; also to provide means for testing the bolt toascertain if it is in proper condition for service.

The invention'consi'sts in the specific constnuotionf and arrangement ofparts hereinafter -described iand claimed',distinguishing, features'being the use of one or more taperedplug ends of relatively low tensllestrength-in conjunction with a shank of re'latively' high tensilestrength; the formation of a take-up or compensating recess in one head;and in conjunction with the'latter feature, in the formation of atesting passage communicatlng wlth said take-up re- ,cess,',and--in theprovision of means for effecting! the closure of said testing passagesubstantially as hereinafter set forth.

' In the accompanying drawings, Figure 1, is a central longitudinalsection of my improved stay bolt, both ends 'of which are provided withsoft heads capable of being riveted; Fig. 2, is a central longitudinalsection'of a two piece stay bolt embodying my invention; Fig.3,-a'central longitudinal section of the bolt illustrating amodification Specification a Letters Patent. l Application filed July 1,1508. Serial No. 441,809.

Patented Oct. 3, 19 11.-

of structure; Fig. 4:, is a similar view showing' another. modification;Figl. 5, is a' detail of one end of the shank shown in Fig. 3.

As. is well known, the usual method of fasteningrigid stay bolts toboiler plates is to use a straightthreaded bolt and to peen orrivet'over the ends thereof to make tight joints with the boiler sheets.This riveting of the ends has heretofore involved the use of a bolt ofcomparatiyely low tensile strength, such as iron, copper or copperalloy, and even then if the male and female threads do not fitperfectly, or the riveting is' carelessly done, leaks areapt to occur.Furthermore, in order to attain the requisite degree of tensile strengththe shanks of such bolts have heretofore been= 1i1adej: of comparativelylarge diameter. On the other hand, steel stay bolts have been used, andwould be used generally were it not for the difficulty involved inmaking tight joints with'the'ends thereof and the boiler plates, Henceasteel shank pro vid'edwith ends that will insure tight joints alfordsmany"p -ac tical advantages which I attain by my structure of stay bolt.Since it is obvious that the smaller the diame ter of steel shank thegreater will be its flexibility, and hence the greater" the lateral orbending strain it will stand, I am enabled to materiallyreduce the sizeand weight of the bolt and still retain the requisite degree ofstrength. This re duction in size' and weight also lessens the cost 'ofthe stay bolts; and they occupy less of the water space between theboiler sheets as compared with those heretofore used, therebyfacilitating the circulation of water, and as a result, rendering thetemperature of the parts more uniform and obviating excessive strain onthe shanks of the bolts.

Theshank S is made preterably'of metal of comparatively high tensilestrengthp and relatively small in diameter. Its inner end is formed witha male screw threads, for engagement with the female screw thread a, inthe socket head A, which latter is formed also with an external threada,'for engagement (preferably) with a threaded hole tapped in the thebox plate F. The take-up recess a in the socket head A, is of sufiicicutdepth to afford a margin of adjustment. of

length of bolt as a whole, to compensate for variations in distancebetween the fire box plate F and the shell B. My stay boltis,

thus adjustable within itself after the socket a.; 'plug insertion of agage for the purpose of head A has been secured to the fire box )latcnecessar since the o, 081

F, so that a shank S of uniform and prescribed length may be used withincertain limits or variations of distance between plates.

The socket head A, may be provided with a test or indicator passage a,communicating with the take up recess a and closed by i p. This testpassage a admits of ascertaining the extent ofpenetration of thethreaded inner end .9, of the shank into] the socket head A, todetermine for instance, the shank S, is screwed into the head suf titiently to hold securely.

flVhen the socket head A is to be riveted to the plate I! as in Figs. 1and 3, a dolly 92111 is introduced through the perforation b inlthe)late B to sustain said socket head 1 l 7 A, during the operat ion.

The test passage (1., may be closed by plugs '0f various terms. in Fig.1, a screw plug is used, while in. Fig. 3, the plug is drivi a". some;to spread late-rally into a groove r a in the head. In Fig. 4., the testpassage consist t a continuation of the take-up ,reeesr. closed by athreaded plug.

By making the test passage c and takeup recess of uniform diameter,with'a dontinuhus lemale thread for engagement with the male threads ontie/shank S, and by threading both ends of the latter, as shown in F 4;,both the outer head C aitd the socket head A, may be securely fixed andniadfe tight in the plates F andyB before inserted,--the latter beingintroduced through the socket A. In such manne'ifit'hc shank is notsubjected to strains which it, otherwise would sustain and which areincitlent to the securing at the heads A and in the plates .F aiid G. Bypro viding the inner end of the shank S with a telltale bore .9", thecracking or fracture of the shank S at this point would be indil 1 catedby the presence of water in the takeup reces (L to be ascertained by theremoval of the plug 7).

I re or to make either one or both of ft I J the heads A, \i, ta pdnnexternally, w1th male threads forengag; meat with correspondin taperingtermne threads in the plates. has nl ig. i, the sot-hot; head A,

"consists of aplug tapered and threaded externall in a direction0))0Slt0. to the an threaded external taper termed directly on the outerend of the shank 5.. a similar arrangement helng shown in Fig. t,excepting that the outer head (J is in this case ahead C is tapered. Inthis head is welded around the formed of a separate piece of metalsofter thiilrithe shank S. In Fig. 3, only the outer case, also, theflattened or spread end 8 of the shank S.

'In the-two. piece form of bolt shown in 2; the riveting up of the endsis not I I l l tely tapered heads insure tight; joints. 7

It is to be noted that the shank S-is of to secure Letters Patent is,

1. The combination inf'a stay bolt of the character designated, of athreaded metal shank of relatively high tensile strength and smalldiameter formed with a tell-tale bore in-its inner end, an externallythreaded socket head of less tensile strength formed with a femalethread extending through said head for engagement with the male threadon the shank, and a screw plug engaging said female screw thread andclosing the end of 'said head.

2. The combination in a stay belt of the character designated, of athreaded metal shank of relatively high tensile strength and "smalldiameter, and an externally threaded tapering socket head of lesstensile strength formed with a female thread for engagement with themale thread of the shank,;and with a takeup recess, with a test passage,and with a plug for closing said test passage.

3. The combination of a stay bolt of the character designated, athreaded metal shank of relatively high tensile strength and smalldiameter, formed with a bore in its inner end, an externally threadedtapering socket head of less tensile strength, formed with a/temalethread for engagement with the'male thread on the. shank and extendingthrough said head, and a screw plug. engaging said female screw threadand closing the end of said head. 4-. The con'ibination of twooppositely dis,- posed boiler plates and a joining device consisting ofa head member of relatively low tensile strength screwed into an openingin one of said oppositely disposed plates, and a shank member ofmaterial ofv relatively high tensile strength removably engaging at oneend one of said oppositely disposed boiler plates and removaliilyengaging at its opposite .end the aforesaid head member carried in theopposite of the said two boiler plates; substantially as described.

The combination in a stay bolt'of the character designated, of athreaded metal shank of relatively high tensile strength and smalldiameter and an externally threaded socket head formed with a femalescrew thread extending through the head for engaging the male screwthread on the shank tell-tale' shank of relatively high tensile strengthand a small diameter formed with a tell-tale.

-". gagement with the threaded shank and with the shell of the boilerand a screw plug adapted to engage the internal thread of the plug andclosing the outer end of the v nated, of a threaded metal shank etrelatively high tensile strength and t small diameter, and an externallythreaded I tapering socket head of less tensil a strength 1 formed witha, telltale screw thread engaging 1 with the male screw thread at theshank and extending through said head and'a l screw plug engaging saidfemale screw 1 thread and closing the end of said head.

l l itnesses GEO. M. B'lu'r'r,

l 1 GEORGE S. TIIOMPSON.

l l). \l. Gunmen.

